There is no single "Windows Server 2003 ISO." Microsoft released several editions, each with different maximum RAM, CPU support, and features.
Before downloading a Windows Server 2003 ISO file, consider the following risks and factors: windows server 2003 iso download
The operating system is nearly two decades old. Critical vulnerabilities like EternalBlue (used by WannaCry) affect unpatched Server 2003 systems. There is no single "Windows Server 2003 ISO
If you're considering alternatives to Windows Server 2003, here are a few options: each with different maximum RAM